Visualize the Basins of Attraction

Which start points lead to which basin? For a steepest descent
solver, nearby points generally lead to the same basin; see Basins of Attraction. However, for Optimization
Toolbox™ solvers,
basins are more complicated.

The figure shows the centers of the basins by colored * symbols.
Start points with the same color as the * symbol
converge to the center of the * symbol.

Start points do not always converge to the closest basin. For
example, the red points are closer to the cyan basin center than to
the red basin center. Also, many black and blue start points are closer
to the opposite basin centers.

The magenta and red basins are shallow, as you can see in the
following contour plot.